Abstract
The devices based on plastic film such as optical film, lithium-ion secondary battery and fuel-cell stack have being manufactured by roll to roll system. In this system, the films are finally wound in the shape of roll. The wound roll is shipped to the store and transportation, in some cases, heat-treated under the various temperatures. Then internal stress of wound roll will be changed due to thermal strain and viscoelastic properties. As a result, those elements causes to wound roll defects such as slippage and wrinkling. For the problem, thermo-viscoelastic model of internal stress of wound roll was presented. In the present optimization method, the wind-up tension is gradually changed in the radial direction to minimize the tangential stresses under the constraint of nonnegative tangential stresses. At the same time, we consider the friction conditions to prevent the slippage between web layers due to a decrease of radial stresses and friction force. Successive quadratic programming, which is a typical mathematical programming method, is used as the optimization technique. The optimized wind-up tensions are obtained, and we confirmed theoretically and experimentally that the internal stress distributions are very much improved for preventing both wrinkling and slippage simultaneously.
